Sowing the Trials

Site details
Paddock history: 2010 Barley. April 2011 stubble was burnt and harrowed. In May 2011, the paddock was prickle chained immediately following trifluralin application.

Sowing date: 20 May 2011.

Sowing rate: 5.6 kg/ha; seed size 212,900 seeds/kg.

Variety: Pioneer 44Y84

Plot size: 1.74 m x 20 m.
Herbicide and insecticides:

Date	Crop stage	Product	Rate (per ha)
18 May 2011	Bare earth, incorporated	Lorsban
	Bare earth, incorporated	Treflan®	1.5 L (ch.)
20 May 2011	Post-sowing, pre-emergence	Lorsban	Check with peter
		Endosulfan
		Mouseoff (zinc phosphode)	1 kg
7 July		Mouseoff	1 kg
ca. 27 July	Post-emergence	Intervix®
		Select®

Soil type: Wimmera grey cracking clay (vertosol).

Soil pH_Ca: 8.30 (water), 7.70 (CaCl₂).

Soil available N: 3.9 mg/kg nitrate and 0.9 kg/ha ammonium, equating to 34.8 kg/ha available N in top 60 cm at sowing (17 kg/ha N in top 10cm).
Estimated in-crop mineralisation 40.8 kg/ha N.

Fertiliser: 50kg/ha triple super at sowing plus varying urea rates.

Plant available water: 45.6mm to 60cm depth; 71mm to 100cm depth in early May 2011.

2011 growing season rainfall: Average of 300 mm (1 April – 31 October 2011, Longerenong College Weather Station).

Harvested: .

Method
The trial was sown dry two days prior to rain into cultivated soil with Incitec Pivot/University of Melbourne small plot cone seeder with trailing press wheels. Urea was drilled below the seed at varying rates in the one pass.

Seed was treated with Jockey and Gaucho. The hybrid 44Y84 was chosen as the trial co-operator was using two other Clearfield varieties in the same paddock, and open pollinated early variety (44C79) and a mid-maturing hybrid (45Y82). The 44Y84 gave the opportunity to showcase a new, early maturing hybrid within the same herbicide tolerance group.
A randomised complete block design with three replicates was used to compare three rates of nitrogen with nine timings, as well as control plots which received no urea.

Potential yield calculations:
Potential yield at sowing was calculated as 2.12 t/ha using the modified French-Schultz equation, assuming a water use efficiency of 9.5 kg/ha/mm for a 19 May sowing.
The calculation included plant-available subsoil water to 100cm depth, rather than 60cm, which is used by fertiliser companies and advisers. Soil moisture was measured in early May. Plant available water was determined by using APsoil (CSIRO) soil property figures for upper and lower limits at a nearby property of Trevor McRae. PAW to 60 cm depth was determined as 46mm; to 100 cm depth PAW was 71 mm.

Estimating Fertiliser rates:
The three rates of nitrogen (from all sources) per tonne of potential yield were based on the assumptions of:
1. 80 kg N/ha (used by agronomists)
2. 60 kg N/ha (used by DPI Kerang)
3. 40 kg N/ha (low rate)

When subtracting available nitrogen already in soil at sowing (35 kg N/ha) and the estimate of available nitrogen added to the soil through mineralisation during the growing season (41 kg N/ha), the urea rates applied were:

1. 204 kg urea /ha
2. 112 kg urea /ha.
3. 20 kg urea /ha.

Fertiliser timing:
Timing of application included pre-drilling and topdressing treatments at stem elongation and early flowering, plus combinations of split applications:
1. All urea pre-drilled (20 May)
2. All topdressed at stem elongation (4 August)
3. All topdressed at early flowering
4. Half pre-drilled and half topdressed at stem elongation
5. Half pre-drilled and half topdressed at early flowering.

Trial Layout:
To come.